LITTLE ROCK, Ark. (AP) - A national conservative group launched the first 2014 campaign attack against Arkansas Sen. Mark Pryor Thursday with a television ad that derides the Democrat as President Barack Obama's "best ally" in the state.

The Washington-based Club for Growth announced it would begin airing the ads in Arkansas beginning Friday. Strategic Media Placement, a media buying firm, said Club for Growth bought about $101,000 worth of airtime to run the ads through March 13.

The 30-second spot is likely the first of many attacks from conservatives targeting him as he seeks a third term in Arkansas, where Republicans now hold all but one of the state's seats in Washington. The ad tries to paint Pryor as too closely aligned with Obama, who remains deeply unpopular in Arkansas. It criticizes Pryor's votes for the federal health care overhaul in 2009 and the economic stimulus package that year.

Pryor won re-election easily in 2008 without a Republican opponent. No Republicans so far have announced a bid to challenge him.

"He's supposed to be our senator, but Mark Pryor is really Barack Obama's best ally in Arkansas," the ad says.

Pryor, who announced last year that he was seeking re-election, dismissed the ad as misleading voters about his record.

"People are sick of politics and non-stop campaigns by special interest groups like the Club for Growth," he said in a statement released by his office. "This is the first of what's certain to be an endless array of special interest groups coming to Arkansas to distort the truth about my independence and bipartisanship."

The Club for Growth was a major supporter of freshman Republican U.S. Rep. Tom Cotton's successful bid for a south Arkansas congressional seat last year. Cotton has been mentioned as a potential challenger against Pryor. A spokeswoman for Cotton said he was focused on his job in Washington but would not say whether he was considering a Senate bid.

"There will come a time for politics, but it's not right now," spokeswoman Caroline Rabbit said.

Republican Lt. Gov. Mark Darr has said he's considering challenging Pryor next year, but won't make a decision until after this year's legislative session.

The move came a day after the Club for Growth also made moves against Republican U.S. Rep. Rick Crawford of Arkansas. The group listed Crawford on a website seeking suggestions for primary opponents for nine congressmen, criticizing him for proposing a surtax on millionaires in return for the passage of a federal balanced budget amendment.

Arkansas has turned increasingly Republican in recent years, with the GOP sweeping all four of the state's House seats and winning control of the state Legislature in the November election. Democratic U.S. Sen. Blanche Lincoln lost her re-election bid in 2010 in a campaign where Republicans also painted her as too closely aligned with the Obama White House.